Hi, relatively new to this site but not new to mountain bikes, I ride a Dialled Bikes Price Albert at the mo for trail centres and bike parks thats a steel hardtail with long travel front forks. Ride a 96' rigid Lava dome to the
yard every day and on local off road rides (absoloutely fine for off roading in north herts and cheap to maintain).
Merlin Malt and rock lobster is a good choice, loads of bike for your money, used to ride one and have built my girlfriend a malt 1 and she loves it. On one bikes are deffo also worth a look as are diallled imo
, make sure you get the sizing right, have seen many people get put off mountain biking from poor fitting bikes how tall are you?, im 5"9" and ride 16 - 17" frames typically, that allows me to lower the saddle for technical/downhill sections. I have adjustable travel on the suspension forks as well and find that a useful feature as you can wind the front end down when climbing to keep the front wheel on the ground.
I wouldnt personally recommend a full suss for a first mountain bike, you can develop more skills on a hard tail and it will make you a better rider if you wish to progress, i have ridden full suss in the past but returned to hardtail as i find its less maintenence and more challenging, i also need to avoid any more head injurys due to health so the real hardcore riding is out of the question now!.
It would also be worth thinking about what you will be using the bike for, if its for commuteing on the road to work and shops forget about mountain bikes and get a decent hybrid with a good set of panniers and a rack and if you can face it mudguards, me and the girlfreind share one of these, she doesnt drive so uses this for her main transport and its great, faster and more comfortable than an mtb on the road and no sweaty back from carrying everything in your rucksack, this was my bike when i was temporarily unable to drive and i used it to carry all my climbing gear and even 020 sometimes easier than it would be to carry it in bags. Kona do a good range of hybrids. as do trek, marin, spesh and giant. Hybrids are very practical 99% of the time for most cyclists but are not very cool hence the popularity of mtbs i think.
Sorry for ramblings but will talk about bikes all night (if im not riding them)